In current cellular communication systems, a mobile station communicates with a mobile switching center via a base station subsystem. The base station subsystem typically includes a base station controller that is coupled to a transcoder. The transcoder is coupled to the mobile switching center.
The mobile station may, at times, need to be handed over from its serving base station subsystem to a different target base station subsystem. In current systems, the target base station subsystem initiates the handover. If there is a problem with the signaling links between the base station controller and the mobile switching center, the call might be dropped. This is true even if the base station subsystems are capable of communicating with the mobile station. The potential for valid traffic channels with a loss of signaling is growing with the separation of traffic signals from control signals.
In certain cellular systems, the concept of keeping the handover within the base station subsystem solves a part of the problem, but not completely. The loss of the signaling links could still cause the call to drop, even if the original base station controller is no longer involved with the call. The call can be moved from one base station subsystem to another, but the call is not enabled from the base station subsystems, but rather from the core network.
In current packet networks that include a mesh that interconnects the base transceiver stations and the base station controllers, a means to request the transfer of the call from one unit to another would require standardization in order to manage traffic in the access network.
Connecting a base transceiver station to multiple base station controllers for redundancy to accommodate the failure of a base station controller solves the redundancy problem. However, existing calls would drop due to the inability to inform the mobile switching center that the calls are still up but have been moved to a different base station subsystem.
Thus, a need exists for a method and communication system for changing communication within a communication system without dropping the communication.